Percussion fuze



J. R. JASSE PERCUSSION FUZE May 3l, 1960 3 Sheets-Sheet 1 Filed Feb. 25, 1958 s. m w ...MW l 2..... ,/f/.WA v1 4May 3l, 1960 .n.R. JAssE 2,938,463

PERCUSSION FUZE Filed Feb. 25, 1958 3 Sheets-Sheet 2 J. R. JASSE PERCUSSION FUZE May 3l, 1960 3 Sheets-Sheet 5 Filed Feb. 25', 1958 PERCUSSION FUZE v Joseph Raymond Jasse, Paris, France, assignor to Ste: Hotchkiss-Brandt, Paris, France, a corporation of France Filed Feb. 25, 1958, Ser. No. 717,369 A Claims priority, application France Feb. 26, 1957 6 Claims. (Cl. 10271) The object of the presentl invention is to provide a percussion fuze for a projectile which fuze automatically destroys the projectile and renders the latter absolutely safe before use and when in the launching or firing tube and ensures that it does not explode in the vicinity of the launching tube after having been launched. This fuze is more particularly adapted for projectiles in the form of rockets which are red from a flying machine, with or without a gun effect, and explode in the air whether they reached the target or not.

The firing means of this fuze comprises in combination with a primer carrier, a striker device or unit in two independent parts or sub-units disposed one behind the other forward of the primer, the forward part or subunit being connected to the nose of the body of the fuze by a irst shear member which is capable of being sheared upon impact and constituting a dash-pot having a retarding liquid, whereas the rear part or sub-unit, which is subjected to the action of an automatic striking spring, comprises two elements which are interconnected by a second shear member, one of said elements constituting the vstriker pin, the latter being held in its inoperative position withdrawn forwardly of the primer carried by said primer carrier, in opposition to the action of said automatic striking spring, by an automatically retracted retaining device which retracts when a period of time determined by said dash-pot has elapsed after the launching of the projectile, whereby the projectile is automatically iired and destroyed upon displacement of said rear sub-unit under the eiect of said spring as soonas the retaining device has retracted, whereas the projectile is red upon impact, before automatic destruction of the projectile, by the shearing of both said shear members and the rearward movement of said two sub-units.

Thus, the fuze explodes the projectile either automatically, at a certain distance from the point of launching which is a function of the amplitude of the displacement` of the primer carrier and of the striker pin necessary for ensuring the retraction of the retaining device, or upon impact against an objective or target situated at a distance from the point of launching which is less than the distance corresponding to automatic projectile destruction.

Further features and advantages of the invention will be apparent from the ensuing description with reference to the accompanying drawings, to which the invention is in no way restricted.

In the drawing:

Fig'. 1 .is a vertical longitudinal sectional view taken along line 1-'1 of Fig. 2, that is, in two longitudinal radial planes disposed at 90 to one another but shown to be contained in the plane of Fig. l,` of a percussion fuze embodying the invention;

Fig. 2 is a sectional view taken along line 2-2 of Fig. 1, the'elements situated on the right side of the axis ofthe fuze shown in Fig. 1 being shown in their normal p'si'tion'at '90' to the part situated on. theleft side of SaidaXiS; 'i

12,938,463 Patented May 3,1, 1969 F-ig. 3 isa sectional view taken along line 3-3 of Fig. 1;

Fig. 4 is a sectional view similar to Fig. 1, showing the fuze at the moment when the retaining device is retracted to permit the striker pin to effect the automatic projectile destruction percussion;

Fig. 5 is a longitudinal sectional view similar to Fig. l taken along line 5-5 of Fig. 6, of a modification of the fuze more particularly adapted for launching with a gun eiect, and

Fig. 6 is a sectional view taken along line 6-6 of Fig. 5 after the part of the latter on the right side of the axis has been turned' downwardly 90 about said axis.

In the embodiment Ishown 'in Figs. l to 4, the fuze is adapted to be combined with a rocket or other projectile Rwhich is more particularly intended to be launched from a ying machine without a gun effect, that is, under its own means of propulsion, the latter being ensured solely by the thrust of the gases of the propelling charge housed in the rocket.

The fuze comprises a body 1 provided at the rear with a screw thread 2 for the purpose of screwing the fuze in the projectile R. Screw-threadedly engaged at 3 on the body 1 is a forward nose 4.

This nose comprises, in alignment on the ax-is X-X, a forward cylindrical aperture 5 to which is connected by two transverse shoulders 6 and 7 a cylindrical recess or bore 8 of larger diameter which coaxially adjoin a lowerV The bore 9 is separated by a transverse Wall or parti` tion 10 from a cylindrical bore or chamber 11, whose axis Y--Y'is perpendicular to the axis X-X. The transverse chamber 11 communicates by way of an aperture 12 witha cup 13 screw-threadedly engaged in a tapped recess 13a in the end of the fuze body 1.

Disposedbetween the shoulder 6 and the wall 10 is a cylindrical guide tube'114 which divides the chamber formed in the body 1 and in the nose 4 by the bores 9 and 8 into an inner axial chamber and an outer peripheral chamber.

Disposed: in the axial chamber is a tiring means A and disposed in the peripheral chamber is a device B adapted to hold the means A in its inoperative position before launching.

Disposed in the transverse chamber 11 is a detonator carrier C. The aperture 12 contains an explosive charge' D which forms a relay and is adapted to ignite the booster charge which in turn ignites the explosive charge or the 20 and 21 respectively inthe fixed guide 14, these two bores being'interconnected by a shoulder 22 in the vicinity of which is located the shoulder 19 of the carrier15 in its inoperative position. t

The primer 23 is disposed in the carrier 15 toward the rear end of the latter and this carrier is extended rearwardly by a tube 24 which extends freely through an aperture 25 formed in the wall 10 and ordinarily extends.

a 4certain distance a into the chamberll containingthe detonator carrier C. 4

The primer carrier 15 is urged forwardly by a spring body, when the projectile is launched, in opposition to.

the action of the spring 31 by a tube 32 which is axially movable in the bore 8 and tends to move rearwardly of the fuze body under the effect of inertia; the sleeve 30 eventually lreaches the position shown in Fig. 4. The rearward movement of the tube 32 is retarded or braked in the known manner by a lug or stud 32fwhich moves along a zig-zag groove 34 formed in the tube 32. The latter constitutes, in combination with the sleeve 30, the essential part of the automatically armed locking or retainingl device B which is completed by a sleeve 35l engaged in the bore 9 of the fuze body 1. This sleeve 3,5 is provided with resiliently yieldable tabs 36 which are adapted to engage a recess 37 in the tube 32 and hold the latter in its position corresponding to the end of its rearward travel (Fig. 4) v The firing means A comprises not only the primer carrier device 15--24 but also a striker device or unit consisting of a forward part or sub-unit P1 and a rear part or sub-unit P2.

The forward part P2 constitutes a dash-pot disposed in the bore of the nose 4. It comprises a cylindrical body 38 provided with a forward transverse end against which isxed, by a rivet 39, a shear plate 40 which is held fast in the nose of the fuse 4 by a formed-over ange 41 and is adapted to shear or break under a predetermined stress. v

Movable in the bore of this cylinder without appreciable play is a piston 42 which a spring 43 biases rearwardly. This piston 42 has in its outer face a flat portion 44 (Figs. 1 and 3) which provides a passage through which a liquid 45 filling the cylinder 38 above the piston 42 can flow rearwardly when the piston moves forwardly. Advantageously, the liquid 45 is, for example, a silicone. Y

In its normal position, the fluid-tightness of the cylinder 38 is ensured by the contact of a lower annular support rib 46, formed under the piston 42, with a washer 47 ofA rubber or like material held on an annular cylinder end 48 which is held fast in the lower end of the cylinder 38 by a formed-over ange or other means.

The other part P2 of the striker device comprises two members: a strikerrpin 49 with a rear point ,50. adapted to strike the primer 23, and a support member or ring ring 52` against the balls 57 through the medium of a' conical face 56 on this ring. These balls 57 f orm retaining members which prevent the part P2 of the striker device from striking the primer 23 under the eiectof the compressed spring 55. These balls 57 are housed in radial apertures 58 formed in the primer carrier 15 and they bear against the cylindrical inner face 20 of the fixed guide 14 which maintains them in their operative ring` retaining position. v

The diameter of the portion 21 ofthe bore of the guide 1-4 is such that for a given forward displacement of the assembly comprising the primer carrier and the part P2 of the striker device, these balls 57 pass. the shoulder 22 and are thus rendered capable of movingl asucient distance outwardly to the position shown in Fig. 4 to release the paft P2 of the striker device.

The detonator carrier C comprises a slide 59 which is movable transversely in the chamber 11 in the direction of the axis Y-Y. It is biased in the direction of arrow f1 (Fig. l) by a spring 60 whichVv is compressed between the slide 59 and a plug 60a. The slide 59 is maintained in the inoperative position shown in Fig. 1 by the engagement of the rear endI of the tube 24 of the primer carrier ina blind hole 61 formedY in the slide 59.y This position is such that a detonator 62, carried by the slide between a forward aperture 63 and a rear aperture 64, is laterally oiset relative to the tube 24 and' the relay D in the aperturewlz. When thel tube 24 is disengaged from the hole 61, the slide 59 is brought to an operative position shown in Fig. 4 in which-the apertures 63 and 64 and the detonator 62 are brought in alignment with the axis X-X, that is, with the axes of the tube 24 and relay D, under the eiect of the spring 60. The spring 60 holds the slide 59 against the endof the chamber V11. The slide is prevented from rotating about the axis Yv-Y in the course of its movement by a stud 65 which is engaged Y in a longitudinally extending slot 66 formed in the slide.

' The fuze operates in the following manner:

In the inoperative position of rest s hown in Fig. l, the striker device. has its rear part P2 held by therretainf ing balls 57 a certain distance away from the `primer 2 3. The spring 55 is compressed and the whole of the tiring means A is held in its rear position so that the tube 24 extends a distance a in the chamber 11 and locks the detonator carrier C in its inoperative position. The balls 27 are held in the recesses 2,9 of the primer carrier 15 Yby the sleeve 30 which is itself held in its forward position by the spring 31. The forward end of the strikerrpin 49 is held a very short distance away from the piston, 42 and the latter is therefore urged against the washer 47 by the force exerted by the spring tingfchain or relay resulting from the lateral offsetA of the. detonator 62, which is locked in this oifset position by the.

tube 24 extendingthe distance a in to the slide 59.

As soon as the projectile R or the like is launched` under the effect of a propelling jet issuing from the'fprcrpelling charge contained in the projectile, the tube 32. is cansedV to move rearwardly relative to the fuze body 1 under the effect of in ertia and moves therewith the. sleeve.

30 which compresses the spring 31,.. Thesel membe1s shiftl from the positions shown in Fig. 1 to the positions.

shown in Fig. 4 and, in releasing the retaining balls 27, release or disconnect the firing means A from the tube 14.

Owing to the zigzag recess 34 and the stud 33 engaged therein, 'the` tube 32 is caused, in the known manner, to` move rearwardly, under the effect of a slight acceleration resulting from the propulsion of the projectile R without there being any danger of prematurely arming the'fuze, that is, v,bringing the tube 32 to the position shown in Fig. 4, if the projectile accidentally fell on its rear end.

.When the fuze ceases to accelerate, the tube 32 is prevented from moving forwardly of theV fuze body -by" the tabs 36 which enter the recess 37 (Fig. 4)..

After `the rearward movement of the tube 32 and-the' sleeve` 30 relative to the fuse body, the primer carrier' 15V and the lrear part P2 of the striker device move for. wardly under the elect of. the-spring 36, firstlywithoutencountering resistance, and thereafter, as soonasthe forward end of thestriker pin 49 encounters therear face of the piston 42,y in opposition to the action. of `the` spring 43 .and of the resistance of the liquid in the dashf pot of the forward part P1.'

The liquid above the piston 42 can only ow through the very small annular clearance between the piston and the inner wall of the cylinder 38 and through the passage created by the iiat portion 44 through which passage the major part of the liquid flows. v

The forward movement of the assembly comprising the carrier and the part P2 is therefore braked or retarded,

the braking effect depending on the total cross-sectional area of the passageway for the liquid between the piston 42 and cylinder 38. vIt will be observed that the fact that a large part of this passageway is formed by the fiat portion 44 constitutes, relative to the solution consisting in utilizing only the annular clearance between the piston 42 and the cylinder 38, an advantage in that it materially reduces variation in the cross-sectional area of the passageway-and in consequence in the braking or retarding effect which is inversely proportional to the cube of the cross-sectional area of the passagewayas a function of machining tolerances.

However, owing to the forward movement of the assembly comprising the carrier 15 and the part P2, the tube 24 progressively moves out of the hole 61 of the slide 59 of the device C but the slide 59 is released only after the tube 24 has withdrawn a distance a therefrom. This withdrawal requires a certain period of time depending on the distance a. This period of time corresponds to the period during which the projectile cannot be exploded by the fuze after the projectile has left its launching or firing device. Thus the projectile is just as safe during this period as it was before it was launched.

As soon as the tube 24 of the primer carrier 1S releases the detonator carrier 59, the latter is moved toward the right as viewed in Fig. l, by the force exerted by the spring 60 and assumes the position shown in Fig. 4.

The forward movement of the movable assembly comprising the carrier 15 and the part P2 continues and, immediately before the piston 42 encounters the forward end of the cylinder 38, the retaining balls 57 enter the enlarged bore 21 of the guide 14 and release the rear part P2 of the striker device. This rear part is thrown against the primer 23 by the force exerted by the spring 55 and eiects an automatic projectile destruction percussion on the primer 23 and the projectile is caused to explode.

If the projectile encounters an obstacle, for instance the target, before automatic destruction but after the movable assemblage comprising the carrier 15 and the part P2 has moved forwardly of. the fuze body 1 a distance at least equal to a, the forward part P1 of the striker device which had been held in position up to then by the shear plate 40, is pushed inwardly of the fuze body after shearing of the plate 40 and shifts the striker pin 49 rearwardly.- TheV pin 53-is then sheared since the ring 52 is prevented from moving rearwardly by the balls 57. The completely released striker pin strikes the primer 23 and effects an impact ring of the projectile.

The inertia of the relatively great weight of the head P1 constituting the dash-pot of the striker device causes a certain delay in the impact firing of the projectile.

Figs. 5 and 6 show a modiiication for a rocket or projectile R1 adapted tovbe fired with a gun effect, that is, with a firing or launching charge which is independent of the projectile. The arrangement is very similar to the previously-described arrangement and differs therefrom only in the following respects:

The delay in the arming which was caused in the first embodiment by the zigzag recess 34 and the stud 33, is dispensed with, the sleeve 30a being urged forwardly in the fuze body directly by the spring 31 and this sleeve comprising in its inner face therrecess 378 which cooperates with the locking tabs 36.

The guide 14a is disposed directly between the rear face 67 of the fuze head or nose 4and the transverse;

When the projectile is tired, the sleeve 309' movesY rearwardly in the fuze body, in compressing the spring 31, and releases the balls 27.' When the projectile ceases to accelerate as result of the gun effect; the sleeve is pre vented from moving forwardly relative to the fuze body by the tabs 36 which engage the recess 37a. Further,

the primer carrier 15 and the part P2 of the striker de-v vice are caused to move forwardly by the force exerted4 by the spring 26 and thenceforth the operation of the fuze is identical to that of the fuze described herein` before.

In this modification, the projectile -associated with thel fuze is rendered safe for a period of time after it has been fired from the launching device or gun by arranging that the distance a the tube 24a extends into the blind hole of the detonator carrier C is greater than the clearance b provided between the forward end of the striker pin 49 andthe piston 42 of the head P1 constituting the dash-pot of the striker device, so that, after Ithe clearance b has been taken up, the following forward travel through the distance (a-b) of the movable assemblage (P2, 15") for releasing the detonator carrier C requires a certain period of time owing to the braking or retarding action of the dash-pot P1.

In this second embodiment, as in the first embodiment, the liquid contained in the dash-pot P1 iiows essentially through the passage formed by the flat portion 44 in the outer face of the piston 42. However, it will be noted that in both cases this solution is not essential. If desired, the liquid could be made to ow solely through an annular passage between the bore of the cylinder 38 and the outer face of the piston 42, provided the manufacturing tolerances are respected. In this case, it is advantageous to construct the piston of a material having a coeicient of thermal expansion substantially greater,

than that of the material constituting the cylinder 38, so as tocompensate variation in the viscosity of the liquid 45 of the dash-pot as a function of the temperature, by

a corresponding variation in the cross sectional area of` the passageway. Thus the cylinder 38 could advantageously be made of an aluminium alloy or of-brass and the piston of methyl polymethacrylate is the liquid 45 is asilicone whose viscosity varies from about l` to 5 befV invention as deiinedfin the appended claims.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

l. In a percussion fuze provided with a muzzle safety and for automatic destruction of a projectile having forward and rearward ends, in combination: a fuze body including a detachable nose extending from said body in forward direction, said body and said nose having a longitudinal axis; in said body, a rear housing transverse to said axis; Ia detonator carrier including a mobile detonator in said housing for movement between a laterally retracted inoperative position and a central operative position in which said detonator is disposed along said axis; a resilient device bearing against said detonator carrier to urge the same Ifrom said inoperative position into said operative position; in front of said housing, a single tiring mechanism longitudinally movable in said body along said axis from a rear position of rest, in which said ring mechanism projects by a predetermined amount into said housing to immobilize said detonator carrier in its inoperative position, said ring mechanism comprising a primer and a striker pin and being a percussion mechanism on: impactl as well as an .automatic percussionmechantsu1;``

upon a forward displacement of given amplitudev greater: thansaid amount; a spring urging said ring mechanism Iforwardly; forward of said mechanism, a dash-pot illcluding a braking liquid and comprising a` cylinder including a solid forward end and an annular rear end, a movable piston in said cylinder and a spring between said solid forward end `and said piston'to urge. said piston into4 a position of rest against the annular end.; and a shearable its rearward. position of rest in which it is engaged in the v rearward transverse housing.

2. In a percussion fuze, provided with a. muzzle safety and for automatic destruction of a projectile having front and rear ends,l in combinatioml a fuze body including a detachable nose extending from said body in 4forward di-Y rection, said body and said nose having a longitudinal axis; in said body, a rear housing transverse to said axis;

a'detonator carrier including aV mobile detonator movable,k

in said housing between ay laterally retracted inoperative position and a central operative position in whiCh said detonator is disposed along said axis; a resilient device bearing against said detonator carrier to urge the latter to pass from said inoperative position t said ,operative position; forward of said housing, a single mechanism for percussion on impact and automatic percussion and longitudinally movable in said body along said axis from a rear position of rest in which said tiring mechanism projects by a determin'able amount into said housing to immobilize said detonator carrier in its inoperative position, said mechanism comprising a rear primer carrier including a primer, a striker pin, an automatic percussion spring to urge said striker pin against said primer, a movable retaining device movable between an operative position land a retracted position and automatically retractableV under the thrustV of said percussion spring to keep the striker in operative position, yaway fromy the primer, a

longitudinally xed member having a surface for guiding` and maintaining said device inoperative position in opposition to the action of said spring, said surface ex tending forwardly of the most rearward position of said retaining devicer corresponding to the rearward position of l rest of the4 firing mechanism over a length greater than said amount by which said mechanism projects into the rear transverse housing, and, a shear member connecting said striker to said retaining device;-y a spring urging said firing mechanism forwardly; forward of said mechanism,-

a, dash-pot including a braking liquid and Comprising Val cylinder including a solid forward end and annular rear' end, a piston movable in said cylinder and a spring between said solid forward end and said piston to urge saidi piston into a `position-ofv rest against the annular end; a

further shear member connecting said cylinder to, saidfl nose so that the piston, at rest against said annular end, is placed in abutting position infront of the forward end v of said tiring mechanism which, in turn, is in its rearward position of rest, for which it is engaged in they rearward transverse, housing.

A fuze according to claim 2, wherein the' primer carrier has at least one radial aperture and the retaining device of the striker comprises in combination: a support member xed to said striker pin by said shear member and at least one retaining member movable inl said aperture between an operative position and a retracted position, the support member and said retaining member having conjugated shapes such. that said member auto-V matically tends to drive the retaining member toward its, retracted position, said. surface terminating forwardly at a position such that the distance'from said position Vto the Y point of contact of the retaining member against said sur.v face is greater than said amount with the tiring mechanism in its rearward position of rest. v

4. A fuze, according to claim 3 comprising a longitu;

dinal fixed tubular guide in which slides the primer car-` rier and the inner surface of which constitutes the first said surface, the. retaining device including a plu# rality of balls each engaged in an aperture of the primer carrier, said support member having the shape of a ring in the shape of a truncated cone bearing against said balls so asl to cause their automatic retraction when they reach the front end of said guide surface.

f 5. A Ifuze according to claim 4, wherein the percussion device is constituted by the striker pin and the support' member connected yby thetirst said shear member slides in; a forward tubular extension included by said primer cars rier, said extension constituting a housing for said automatic percussion spring.

6,., A fuze according to claim 5, comprising a ring` fixed on said tubular extension ofthe primer carrier and serving as a support for the forward end of said percussion spring, whilesaid striker pin slides freely in said 

